An obesity epidemic is leading to an epidemic of obstructive sleep apnea syndrome (OSAS) which is present in 50 percent of the morbidly obese. OSAS leads to cardiovascular (CV) and cognitive morbidity, insulin resistance (IR), and increased mortality. Our preliminary data suggests that cancer risk is increased in OSAS. Obesity, found in about 80 percent of OSAS cases, increases risk of IR, CV disease, cancer and death. Obesity is linked to low socioeconomic status (SES). The overall premise of the proposed research is that although there is an association between obesity and OSAS, both obesity and OSAS independently determine health status. Use of health services will be used as a surrogate of health status. We will link 5 databases to track OSAS cases, use of health services, drugs and death, to obtain data in cases and controls matched by age, gender, neighborhood, doctor and in some aims, BMI. Hypothesis 1: The relationship between OSAS and health status (defined as total health care cost or disease specific health care cost) is influenced (modified) by obesity and SES. Aim 1a: In male and female OSAS, determine the relationship of SES and obesity on the severity of sleep apnea. Aim 1b: In male and female OSAS cases, determine the relationship of SES and obesity on health status and response to treatment as measured by health care costs. Hypothesis 2: The mortality of obesity is in large part mediated by OSAS. Aims 2(a-c): Examine death rate of OSAS cases and matched controls up to 12 years after diagnosis to determine the impact of gender, age and body mass index. Hypothesis 3: Chronic obesity-related co-morbidities (e.g., diabetes, osteoarthritis, cancer) negate the positive effects of treatment of apnea on overall health. Aim 3: Determine the development and progression of new co-morbidities in OSAS to examine impact of obesity, gender, and treatment status. Significance: The research will examine the interrelationships between OSAS and obesity and their impact on morbidity, mortality, and treatment outcome. This research may show that OSAS is a cause of the high death rate in obesity, making OSAS, not just obesity, a major public health problem. [unreadable] [unreadable] [unreadable]